Zeolite beta is a known zeolite which has been shown to possess activity for hydrocarbon conversion and which has a number of interesting and useful properties. As disclosed in U.S. Pat. No. 4,419,220 it has been found to possess activity for paraffin isomerization in the presence of aromatic components in hydrocarbon feeds such as gas oils and this property may be exploited in the production of low pour point, isoparaffinic products such as jet fuels, other middle distillates and lubricants of high viscosity index and low pour point. European Patent Publication No. 94827 discloses a process in which heavy oils are simultaneously subjected to hydrocracking and dewaxing using a catalyst based on zeolite beta which also contains a hydrogenation component; the process is able to effect a bulk conversion of the oil white, at the same time, yielding a low pour point product. The ability of zeolite beta to isomerize paraffins may also be exploited in the production of gasolines by catalytic cracking, either in fluid bed (FCC) or moving, gravitating bed (TCC) catalytic cracking processes. European Patent Publication No. 186,446 discloses a catalytic cracking process employing a mixture of zeolite beta and a faujasite cracking catalyst for the production of gasoline of improved octane and of improved low pour point distillates by catalytic cracking processes.
In spite of its interesting and useful properties, zeolite beta still presents some problems in practical utilization. One of these is its hydrothermal stability. For catalytic cracking, in particular, the zeolite cracking catalyst must withstand very severe deactivating conditions in the regenerator where the cracking catalyst is oxidatively regenerated with an oxygen-containing regeneration gas. During the regeneration process, the coke which accumulates on the catalyst is combusted to form carbon monixide and carbon dioxide together with water which is formed from the hydrogen content of the coke and from the hydrocarbons entrained with the catalyst. Under the high temperatures prevailing in the regenerator, the water is present in the form of steam and produces a severe deactivating effect on the zeolite resulting in the loss of crystallinity, activity and selectivity. Is is therefore desirable to improve the stability of zeolite beta containing hydrocarbon conversion catalysts, especially for use in catalytic cracking processes.